Distributing binder over fibrous materials



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untrue s'mrss ERNEST d. PEEHER F LANGAETEE, PENNSYLVANIA, DILLON E. SMITH, OF PEKSACOL A FLGEIDA, AND CLABENGE C. VOG'T, 0F LANCASTER- PENNSYLVANIA, ASSIGNOBS '10 ABEQTEQNG CUBE COMPANY, 0F LANCASTER, EEEBIEYLVANIA, A. CGBPOEATION O1 EENNSYLVANLA nrsrmurrue BINDER oven, rra nous Mommas Ho Drawing. Continuation of application Eerial No. 236,359, filed Itovember 28, 19. 52. This application filed August a, 193th serial no. 172,352.

The present invention relates to a process of distributing a binder over fibrous materials and to the article produced thereby, and more especially to a process wherein the binder is distributed uniformly and in a desired minimum amount to the surface of the fibers. The process is particularly applicable to the distribution ofa binder over fibrous materials which are afterward formed or molded into fibrous articles.

Various methods of coating the fibers of fibrous materials have been employed or suggested. These processes have included saturating a dry mass of the fibrous material with a liquid hinder or a solid binder in liquid solution and evaporating the solvent. In such processes, a considerable amount of binder is required to coat the fibers. Moreover, the fibers because'of their dry porous condition, tend to absorb the binder and its solvent as Well further increasing the amount of binder and solvent necessary. Tt has also been proposed to apply binding material to the fibers in the form of an emulsion. This requires the formation of an emulsion with the presence of emulsifying agents which may be objectionable in the completed article and have to be removed during the process. It has also been suggested that materials such as sand, cla r or fibrous materials be first wetted with water and stirred into a plastic mass of asphaltto form paving material. The resultant mass has been in the nature or a plastic paving composition. It has also been suggested that solid resins be finely divided and mixed with pulp, which is afterwards heated.

We have found that a binding material can be economicall and uniformly distributed over the fi ers of a fibrous mass with the desired minimum coating of the binder on the fibers, by formin a fiuid pulp oi the fibrous material and ad ing to it and mixing in the binding material thinned with a solvent to sufiici'ent fluidity to form thin liquid films by adsorption onto the surfaces of the fibers. Neither emulsification of the binding material nor heat is required to efiect the distribution of the binding material over the fibers. The distribution of and without such as to be nonsoluble or difioultly soluble in the liquid which forms the fluid pulp suspension. The fiuid pulp is in the nature of a suspension in the fluid, usually water, of the fibrous material, the proportion of the water to the fibrous material being large, as distinguished from the mere wetting or soaking of a fibrous mass with water.

The pulp should be of sufiicient fluidity so that when it is beaten or otherwise agitated, the solution of the binding material can be readily broken up into droplets which are dispersed throughout the fluid pulp. We I have found that the fluidity of the pulp is important in getting a thorough dissemination and distribution of a minimum amount of binder in the form or thin films uniform- 1y applied to the fibers throughout the mass. The pulp is in the form of a suspension in the liquid as distinguished from being merely wetted or soaked by the liquid.

The following is a specific example of our process:

A fluid pulp such as a paper pulp or a pulp for making a fiber-board is formed having an excess of water to render the pulp sulficiently fluid to be handled by, the usual pumping machinery for handling pulps.

The large excess oi water is also necessary in order to get uniform distribution and application of the desired minimum amount of binder to the fibers. The amount of fiber to water is not over about 5 to 10%, although i is added to it and thoroughly stirred into the fluid pul at normal room tem eratures heating. In the case 0 making 2 mousse a fiber-board, a binder of equal parts of asphaltum and stearine pitch is preferably employed. The asphaltum and stearine pitch are substantially non-soluble in water. The asphaltum and stearine pitch are brought into a liquid condition with a solvent which is also substantially non-soluble in water, such as petroleum naphtha, which can be later evaporated. Usually an amount of naphtha about equal in weight to the asphaltum and stearine pitch is used. This solution of asphaltum and stearine pitch to an amount of about 1d% of the weight of the dry pulp is added to the suspended pulp and is thoroughly stirred or beaten into the pulp until the binder is uniformly distributed over the pulp fibers. The fibers have been previously saturated with the water so that the binder is apparently applied to the surfaces of the fibers, as distinguished from the absorption of the binder and solvent the fibers which would take place if the fibers were dry.

The liquid binder solution does not have to be emulsified or finely divided, but can be simply dumped into the beater or other stirring device containing the pulp and the stirring carried out to disseminate the binder over the fibers with a uniformity comparable to that obtained when adding the binder in a fine water emulsion. The large amount of water in proportion to the fiber and to the binder serves to cause the even distribution of the binder over the fibers held in suspension in the liquid pulp.

The process is economical in that no emulsifying agents are needed and the solution of the binding material can be simply dumped into the beater and beaten into the cold liquid pulp.

During the beating of the fluid pulp, the body of the binding material solution which is dumped in is broken up into droplets which are readily dispersed and disseminated throughout the mass of pulp because of its fluid condition, and since the droplets are non-miscible in the water, they are adsorbed onto the surface of the fibers. The presence of the fiber in the pulp suspension probably contributes to the breaking up and dispersion of the liquid into small separated droplets. The beating of the pulp forms a fluid droplet suspension of the relatively small amount of liquid binder which is nonmiscible with the water, and the binder, while in such fluid suspension, is uniformly distributed and adsorbed in a liquid condition onto the surfaces of the fibers, giving a distribution comparable to that obtained with the use of emulsions, but without the presence of objectionable emulsifying agents or the steps of preparing the emulsion.

After the binder has been stirred into and distributed through the fluid pulp, the pulp may be run through suitable forming machines, such as pulp-board machines, to

form sheets which may be dried and are then ready for use. in the case of such articles as pulp or fiber-boards, a relatively small amount of binder is required, and the above process allows such binder to be uniformly distributed and applied as surface coatings to the fibers to cause the desired adherence of the fibers in the completed board with a minimum of binder.

The invention, however, is not limited to mailing pulp or suspensions of fibrous mate rials which are to be used for making paper, pulp-board or fiber-board. It can be utilized to great advantage in malzing an insulation board, which is light and porous. L" can also be used to distribute the binder in greater amounts to make fibrous objects which are to be dense or waterproof, or which are to be molded or highly compressed, either with or without heating.

In all cases, the amount of the distributing liquid, such as the water, is large compared with that of the fibrous material and the binder, since the excess of the distributing medium, such as water, is requisite to produce the desired even distribution of the binder over the fibers. The process is therefore applicable to fibrous materials, in general, including paper pulp and other fibrous pulps made from various materials.

lVhile water is the preferred distributing medium in making the liquid pulp or fibrous suspension, other distributing mediums might be employed, such as alcohol or other liquids which do not act as solvents for the binder employed.

While bituminous binding materials such as asphalts and pitches dissolved in suitable volatile solvents are the binders usually employed in making fiber-boards, other binders may be used which are brought into a sufficiently fluid condition by a suitable solvent. Oils, such as linseed oil, may be thinned by suitable solvents and distributed over the fibers by this process. As examples of other binders may be cited the nitrocellulose materials dissolved on nitrocellulose solvents, varnishes dissolved on various varnish solvents, wax tailings dissolved in petroleum naphthas, etc. In any case, the solution of the binder material as added should be sufiiciently fluid so as to form thin uniform films by adsorption onto the surfaces of the fibers.

The present application is a continuation of our earlier copending application Serial No. 236,359, filed November 28, 1927.

While we have specifically described the preferred embodiments of our invention, it is to be understood that the invention is not so limited, but may be otherwise embodied and practiced within the scope of the following claims: 4 4

memes 3 We claim: 7 water suspension so as todistribute the hi- I. The process of dissriboting bindin mstummous binder in liquid form over the terial in liquid formf through e 13 was fibers.

material, which oomgrises forming e fluid In testimony whereof we have hereunto suspension of ibe fi sous materiel and s set our hands. 70

binding materiel and as solvent therefor, in s- ERNEST J. PIEPER- suspending liquid in which the binder and. v DILLON F. SMITH.-

the solvent are suhstsmfiielly non-soluble CLARENCE G. VOGTn and stirring the suspension to distribute the liquid solution or the binder on the fibers, I -75 2. The process of distributing binding material in liquid form ehrough e fibrous material, which com rises s fluid suspension" or the 1% nine meeerisl end as binding materiel thinned with e, solvent to 3 suficieni fluidity who form thin liquid 1 m: by adsorption onio the surfaces of the fibers in e suspending liquid in which the binder end its solvent are substantially non-soluble, m and stirring she suspension so es to disiigbuie the binder in liquid iorm over the e ers. I 3. The, process of distributing binding material in liquid form through e fibrous material, Which-comprises forming e fluid suspension of the fibrous msterioi and o binding moteriol thinned with s, solvent to suficient fluidii so normal iemyereiures to 0 form thin liquid films by adsorption onlzo the surfaces of the fibers in s suspending liquid in which the binder and its solvent ore substsntieliy non-solul: le end seirring the suspension so as to distribute the binder in liquid form over the fibers.

4. The process of distributing binding material in liquid :Eorm through s fibrous material, which oomprises'forming s water suspension containing not over about of vthe fibrous material and also a binding a material thinned wish a, solveni; of sufioient fluidity toiorm thin liquid films by edsor I tion onto the surfaces of the fibers, both i; e binding materiel and its solvent being sub-- stentislly nonsoluble in Wa ter, end stirring the water suspension so as to distribute ithe binder in liquid form over she fibers.

5. The prooess of distributing s bitumi= ous binding material in liquid form through e fibrous materiel, which com rises f0 a water suspension of the fi rous msteri and the bituminous bindin meierisl thinned with a solvent substantially non-soluble in Waiver to sufioient fluidity to. form thin liquid films by adsorption onto the surfaces of the fibers, and stirring the water susgension so as to distribute the bitous binder in liquid form over the fibers.

6. The process of distribu e biiaumiv nous binding material in liquid form through a, fibrous material, which comprises form ing s water suspension of the fibrous me, terial and s bituminous binding material thinned with naphtha to o sufioient fluidity to form thin 1i uid films by adsorption onto the surfaces 0 the fiber 1, and stirring the 

